Transmission synchronizer



H. H. ROBBINS TRANSMISSION SYNCHRQNIZER Filed March 14, 1938 June 29, 1943.

QN NN VQ S d? h bw @Y x.. w rTll L ww. u." @NN QM' @WN N y ww @NN NN NN NN 'Patented June 1943 TRANSMISSION SYNCHBONIZER.

Henry H. Robbins, Muncie, Ind., assigner to Borg- Warner Corporation, Chicago, Ill., a corporation of Iliinois Application March 14., 1938, Serial No. 195,740 21 claims. (01492-53) lMy invention relates to transmissions of the type employed, 4for example, in motor vehicles wherein there is provided means for effecting synchronization of a pair or pairs of torquetransmitting members preparatory to connecting said members in positive drive'engagerhent with each other. The invention is particularly directed to synchronizing transmissions of the type wherein the synchronizing'ineans comprises friction clutch elements drivingly associated with the respective torque-transmitting members and adapted to be moved into engagement with each other in the initial stage of the shifting movement, and wherein there is-incorporated socalled blocker mechanism for preventing the positive drive engagement of the members prior to the time that synchronization is effected.

An object of my invention isto provide an improved synchronizing transmission wherein one of the synchronizer'elements is -in the'form of a ring having a circumferentially oscillatable and axially shiftable connection with one of the torque transmitting members allowing the ring to be biased to a position in which it blocks axial advance of the movable positive drive member until synchronization is substantially .complete 'Ihe invention further aims to provide a novel and improved lost motion oscillatable connection 'between the synchronizer ring and the member upon which it is mounted, which is extremely simple and inexpensive in construction. To this end, the invention contemplates the provision of a lost motion connection between the synchronizer element and the hub element in the form of a lug on one of said elements projecting radially into a recess in the other element.

interior of the shiftable clutch element.

-is arranged to axially abut the synchronizer element.

Other objects, the advantages and uses of the invention will become 'apparent after4 reading the following specification and claims, and after consideration of the drawing forming a part of the specification, wherein:

Fig. 1 is an axial sectional View through a portion of a transmission` embodying the invention;

Fig. 2 is a partially sectional and partially elevational view taken transversely through the mechanism shown in Fig. 1, as roughly indicated by the ling 2-2 of Fig. l;

Fig, 3 is a'horizontal sectional view taken as indicated by the line 3-3 of Fig. 1;-

` Fig. 4 is an axial sectional view similar to Fig.

y l, illustrating a modification of the invention;

- Another object of theinvention is to provide novel and improved thrust transmitting means for transmitting axial thrust from a shiftable .element of'the mechanism to the synchronizer element, which thrust 4transmitting'means is exceedingly simple and inexpensive in construction,

and yet more effective, certain and durable in operation. To this end, the thrust transmitting element is in the form of a simple split ring of spring material, encircling one of the torquetransmitting members and frictionally engaged against the inner faces of the clutch teeth or internal splines by means of which the shiftable element,Y encircling the saidV one torque-transmitting member, is splined thereto so as to be drivingly engaged therewith and axially movable with respect thereto.- 'I'he split ring is adapted to engage the faces of the shiftable clutch element teeth under its own expanding force, being and" Fig. 5 is a detail axial sectional view of one of the synchronizer clutch facings of Fig. 4.

I have selected, as illustrative of one form in which the present invention may be embodied, a transmission mechanism of the general type illustrated and described in the patent of John C. Buchanan, No. 2,129,342, issued September 6, 1938, wherein a positive drive connection may be established between torque-transmitting members comprising adrive shaft 6 and a driven shaft 1, either in direct drive one-to-one ratio, or in a reduced gear ratio, by axially shifting a movable clutch element, designated generally at 8, so that its clutch teeth 9 move into positive clutching engagement Awith clutch teeth ill formed on the drive shaft 6, or with clutch teeth ii formed on a torque-transmitting member in theform of a gear i2 journalled Von the shaft 1 and in constant reduction geared relationship with the drive shaft 6 through the medium-of a counter-gear assembly, such as is illustrated in said Patent No. 2,129,342 including gears (not shown) meshing with the gear` I2 and a gear I3 formed on they shaft 6, respectively.

The movable clutch element 8 encircles and is splined upon the periphery of a torque-transmitting member I4 by, means of the teeth 9 meshing with splines 33 on the member Il. The latter in turn is splined.' as at I5, on the shaft 1. I'hus the movable clutch element 8 is drivingly connected to the shaft 'i while free to shift axially, and the hub I 4 is likewise free to shift "axially for purposes which will be hereinafter -more fully pointed out. Upon being shifted into clutching engagement with the clutch teeth I0, the movable-clutch element 8 will receive rotative movement therefrom and transmit it in direct one-to-one ratio through the hub I4 to the driven shaft 1. Upon being shifted into clutching engagement with the clutch teeth Il of the torque-transmitting member I2, the movable clutch element 8 will receive rotative movement from the shaft 8 through the reduction gearing including the gears I2and I3 and the,

counter-gear assembly so as to transmit rotationto the shaft 1 at. a reduced rate of speed.

The'movable clutch element 8 is provided with a peripheral groove 28 adapted to receive a shifting fork l29 of a conventional shifting mechanism.

The torque-transmitting member I4- includes Va. hub portion I8 and a radially extending body portion I1 of Adisc-shape. I provide a pair of annular synchronizer elements I8 each including amounting ring portion I9 encircling a respective projecting end portion of the hub I8 and axially abutting against a side -face of the body portion I1 of, the torque-transmitting'member' I4. From the peripheries of the mounting ringl portions I9, rim portions 29 extend axially away from the torque-transmitting member I4. The rim portions are provided interiorly with fricmost' rapid clutchingv action, the grooves are of course relatively fine and closely spaced as indicated, and maybe in the form of" a standard threaded construction such as is commonly used in the threading of pipes, bolts, etc., wherein the distance between adjacent threads or grooves is.

for example, .025 inch. Such standard threads A are of course, as is well known, substantially AV-shaped in cross, section with the edges of the threads attened olf, i. e., the grooves do not meet each other but are separated by sections of the surface of the friction faces 2i.v

When the movable clutch elementi! is movedl axially, it is adapted, in the initial stage of such axial movement, to transmit axial shifting movement to the torque-transmitting member I4 which in turn willimove a synchronizer element I8 into engagement with a corresponding friction clutch element 23. A

Axial thrust is transmitted from the movable clutch element 8 to the torque-transmitting member I4by means 'of an annular ring 89 of spring material -seated in an'annular groove`l 3l formed in the periphery of the body Pportion I1 of the ltorque-transmitting member I4, and

vbiased vunder. compression in yyielding frictional tion clutch faces 2| 'which may be of cc'nven'- tional conical form, adapted to coact with corresponding faces 22 on friction clutch elements engagement with the inner faces of the teeth 9 of the clutch element 8. An annulaily arranged ,Jserles of notches 32 may be provided in the teeth 9, to receive the ring 30 when the shiftable clutch element is in a shown in Fig. 1.

It may-be noted that the groove 3| divides the splines 33 into spaced annular rows of spline. sections between which the ring 30 is engaged so as to positively transmit axial movement to the torque-transmitting member I4 when urged f to do so by the yielding engagement with the 'chronizer elements I8 are provided with lost allel or substantially parallel grooves 25, for the purpose of breaking or dissipating oil films which otherwise tend to form between the clutch faces and to interfere with their proper cooperation. The grooves 25 divide the clutch faces into a plurality of sections each having a wiping edge formed by the junctions between the face sections'and side walls of the grooves 25,-whereby as the face 2I` vrotates with respect to the face 22, these wiping edges will tend to scrape the oil -into the grooves and'establish a much more rapid metal to metal'contact than would be possible with plain uriserrated4 faces.

While I prefer to employ the form illustrated in Fig. 1, the oil lm breaking grooves may take other forms. For example, the grooves may be disposed in helical or threaded formation., such as is illustrated, for example, in the pending application Serial No. 504,084, led jointly by Otto E. Fishburn and myself'on December 22, 1930, and in accordance with the well known practice of helically grooving or threading the surface of one of two conical friction clutch faces for the purpose of securing a non-slipping clutching engagement where oil lms are present, as disclosed, for example, in U; S. Patent No. 1,102,402,

, issued July 7, 1914, to W. S. Gubelman, and. U. S.v

Patent No. 1,657,265, issued January 24, 1928, to Hans Ludwig. Such a helical groove construction is illustrated in Figs. 4 and 5 of the drawing herein, whereinthe helical'grooves on the inte-` rior of the facing 24, are indicated at 25a.. For

shifting clutch element 8.

The mounting ring portions I9 of the synmotion drive connections with the torque-transmitting member I4 in the form ofl lugs 26 projecting radially inwardly from the inner peripheries of the mounting rings I9 and received in axial notches 21 formed in theprojecting porv tions of the hub I6. The notches 21 arewider than the lugs 26 so as to allow limited relative oscillating movement between the synchronizerV I elemleiits I8 and the torque-transmitting member v Projecting radially outwardly from the extremities of the rim portion 2l)V of the synchronizer. elements I8 are a series of blocker teeth 34 between which the teeth 9 of the movable clutch element 8 must move in order to reach the clutch teeth I8 or II with which `positive drive engagement is to be established. blocker teeth 34 may have their ends facing the teeth 9 chamferedas at 35, and the ends -of the teeth 9 may be correspondingly chamfered, as at 36, so that movement of the movable clutch element 8 in the direction of the relative xed clutch teeth II or I9 may cause the registering chamfered surfaces 35 and 36 of the blocker teeth and clutch teeth respectively, to contactv along surfaces disposed angularly with respect to the axis of rotation of the parts at such times as when the teeth 34 are not in direct end to end register with the splines 33 on the torque-transmitting member I4. This condition will exist whenever one ofthe two torque-transmitting members to be interconnected, such as the' member I4 and the gear I2, isrotating at a speed different from that of the other of said members,

central or neutral position, as4

The`

periphery of the ring I0.V

so as'to cause the synchroniser ring il to move to one#` of the two limits of its lost motion drive connection with the torquehtransmitting mem# ber Il as a result of the initial engagement of the clutch faces Il and 22.'

As the members attain synchronization, however. there will bea momentary reversal of the relative rotatimi of one member, relative to the other, such as to cause the synchroniser ring to move toward the other limit of its lost motion connection, and in so moving. it will lreach 'a position wherein"`the' blocker teeth Il will momentarily register with the teeth Il so as to allow the teeth l of the movable clutchelement l to move into the spaces between theblocker teeth Il, and thence on into clutching engagement A3. In a synchronizing transmission, a pair of coaxial torque-transmitting members, a movable jawclutch element carried by one of said members and adapted to be moved axially into engagement with a Jaw clutch element carried by the other member thus to establish a positive `drive connection between said members, a syn.-

chronizer element driven by said one member and adapted to be moved axially into mensual in said groove and resiliently engaging the intewith the teeth i0 or Il, asthe case'may be. This.

movement is aided by the chamfered surfaces tl and It, in a well known manner.

In making this movement, the movable clutch element I will move relative to the torque-transmitting member Il which has been stopped from further axial movement by the engagement of the synchroniser clutch faces Il and 22. In thus moving relative to the torque-transmitting member il, the shiftable clutch element I will slightly compress the thrustlring Il, causing the latter to slide out of the notches I2 and into engagement with the straight portions of the inner faces` 'of the teeth I. 'Ihese straight portions of the rior of the ring, thus maintaining at all times.

the frictional drag engagement with the inner faces of the teeth 8. x.

If desired, the notches I2 may be dispensed with, and the thrust of the shiftable clutch element l transmitted through the torque-transmitting member I4 solely by thei'rictional drag of thel inner faces of the teeth i against the Such a construction is shown in Fig. 4. I

I' claim:

1. In a synchronizing transmission, a pair of coaxial torque-transmitting members, a movable jaw clutch element carried by one of said members and adapted to be moved axially into engagement with a jaw clutch element carried by the other member thus to establish a positive drive connection between said members, a synchronizer element driven by said one member and adapted to be moved axially into frictional driving engagement with a friction clutch element carried by said other member-so as to effect synchronization of said1members, and an annular thrust member of spring material arranged coaxially with said torque-transmitting embers, having an axial thrust transmitting connection with said synchronizer element and being biased under compression in radially outwardly directed yielding engagement with the interior of said 'movable clutchvelement, whereby to transmit axial movement from said movable clutch elerior of said'movable clutch element under its own expanding force, whereby to transmit axial movement from said movable clutch elementv to said synchronizer element through the medium of said one torque-transmitting member.

4. A transmission as denned in claim 1. wherein said movable clutch member has in its said interior a depression in which said annular thrust member is initially engaged.

5. In a synchronizing transmission, a pair of coaxial torque-transmitting members, a movable law clutch elementhaving internal teeth whereby it is splined in encircling relationship upon one of said members, and adapted to be moved axially to bring said teeth into clutching engage,

ment with cooperating Jaw clutch teeth on` the other member, thus to establish a positive drive connection between said members, a' synchronizer element driven by said one member, having an internal friction clutch face, and adapted to be moved axially into frictional driving engagement with a cooperating vclutch face on said other member so as to effect synchronization of said members, and an annular thrust member of spring material arranged coaxially with said Atorque-transmitting members, having an axial thrust transmitting connection with said synchronizer element and being biased under ccmpression in radially outwardly directed yielding engagement with the inner faces o f the teeth of said movable clutch element.' whereby to transmit axial movement from said movable clutch element to said synchronizer element.

6. A transmission as defined in claim 5. wherein said annular thrust member is adapted to yield axially with respect to said movable clutch element during shifting of thelatter, but remains at all times in engagement with the interior of the teeth of said movable clutch element.

7. In a synchronizing transmission, a pair of coaxial torque-transmitting members, a movable jaw clutch element having internal teeth whereby it is splined in encircling relationship upon one of said members, and adapted to be moved axially to bring said teeth into clutching engagement with cooperating jaw clutch teeth on the other member, thus to establish a positive drive element driven by said one member, having anv internal friction clutch face, and adapted to be moved axially into frictional driving engagement with a cooperating clutch face on said other member so as to effect synchronization ofsaid members, and a split ring of spring material arranged coaxially with said torque-transmittingmembers, having an axial thrust transmitting connection with said synchronizer element and being biased under compression in radially outwardly directed yielding engagement with the inner faces of the teeth of said movable clutch element, whereby to transmit axial movement from said movable clutch element to said synchronizer element.

8 In a transmission synchronizer, a torquetransmitting member, a driven member arranged coaxially therewith, a movable clutch element encircling said torque-transmitting member and having internal teeth cooperating lwith splines on said member to form a splined connection therewith whereby it may be moved axially td bring said teethinto .engagement with a jaw clutch element carried by said driven member thus to establish a positive drive connection between 'said members, a synchronizer element having an oscillatory lost motion driving connection with said torque transmitting member and having an internal friction clutch face adapted to be moved axially into frictional driving engagement with a cooperating external clutch face aaaaovo ments being provided with a radially projecting lug and the other' of said Velements providing an axially extending space into which said lug extends to form a' lost motion circumferentially on said other member so as to effect synchrog nization of said members, said clutch faces being conical and one of said faces having oil grooves therein for reducing the oil film otherwise tending to form between said faces, and a split ring thrust member of spring material encircling said torque-transmitting member, having an axial thrust transmitting connection with said syn- 'torque-transmitting members mounted in :axial alignment, a movable jaw clutch element ca-rried by one of said members and adapted to be moved axially into engagement with a J'aw clutch element carried by the other member thus to establish a positive drive connection between said members, a synchronizerelement having a lost motion circumferentially oscillatable and axially shiftable connection with said one member andv adapted to be moved into frictional driving engagement with a friction clutch element carried by said other member so as to effect synchronization of vsaid members, and blocker means carried by said synchronizer element and adapted to be shifted into blocking relation to said mov-l able clutch element by the initial engagement between said synchronizer and friction clutch elements, whereby to prevent said movable clutch element moving into positive clutching engagement with said other torque-transmitting member until synchronization is substantially complete. 4

12. In a synchronizing transmission, a pair of coaxial torque transmitting members, jaw and friction clutch membersdrivlngly associated with one of said torque transmitting members, ay hub element mounted upon the other torque transmitting member, a`jaw clutch sleeve encircling and drivingly connected to said hub element, and axially shiftable thereon into positive clutching engagement with said jaw clutch member so` as to establish a positive drive connection between said shafts, an annular synchronizer element oscillatable connection between said elements, and blocker means carried by said synchronizer element and adapted as a result of frictional engagement between said synchronizer element and said friction clutch member to be biased in a position blocking vaxial advance of said sleeve to positive clutching position until synchronization is substantially complete.

13. In a synchronizing transmission, a pair of coaxiall torque transmitting members, jaw and friction clutch members drivingly associated with 'one of said torque transmitting members, a hub element mounted upon the other torque transmitting member, a Jaw clutch sleeve encircling, drivingly connected to and axially shiftable upon the periphery of said hub element into positive clutching engagement with said jaw clutch member so as to establish a'positive drive connection between said torque transmitting members, and a synchronizer ringhaving a lost motion circumferentially oscillatable and axially shiftable connection with said hub element, adapted under axial pressure to establish a synchronizing frictional driving connection with said friction clutch member, and including blocking means adapted as the result of frictional engagement between said ring and said friction clutch member to be biased in a position blocking axial advance of said sleeve to positive clutching position until synchronization is substantially complete.

14. In a synchronizing transmission, a pair of coaxial torque transmitting members, jaw and friction clutch members drivingly associated with one of said members, said jaw clutch member andthe other of the said torque. transmitting members being formed with alignable peripheral teeth, a jaw clutch sleeve encircling and having internal teeth in sliding splined engagement with the teeth of said other torque transmitting member, and shiftable axially to bring said internal teeth into positive clutching engagement with the teeth of said jaw clutch member, thus to establish-a positive drive connection between said members, and a synchronizer ring having a lost motion circumferentially oscillatable and axially shiftable connection Ywith said other torque transmitting member, adapted under axial pressure to establish frictional synch-ronlzing engagement with said friction clutch member-and including blocker means adapted as a result of frictional engagement between said ring and said friction clutch member to be biased in a position blocking axial advance of said sleeve until synchronization is substantially complete.

15. A synchronizing transmission as defined in claim l2, wherein said lug is formed integrally with said synchronizer element and projects radially inwardly into said space, the latter being formed in said hub element.

16. In a synchronizing transmission, a torque transmitting member, jaw and friction clutch having a friction clutch face for coaction'wlth members drivingiy associated therewith, a torque transmitting element coaxial with said members, said element and said jaw clutch member being formed with alignable peripheral teeth, a jaw clutch sleeve encircling and having internal teeth in sliding splined engagement with the teeth of said element, and shiftable axially to bring said internal teeth into positive clutching engagement with the teeth of said jaw clutch member, thus to establish a positive drive connection between said torque transmitting element and member, and an annular synchronizer element having a friction clutch face for coaction with said friction clutch member, one of said elements'being provided with a lug and the `other of said elements having a'space into which said lug extends to form a lost motion circumferentially oscillatable driving connection between said elements.. and blocker teeth carried by said synchronizer element, alignable with the internal teeth of said sleeve, and adapted as a result of frictional engagement between said synchronizer element and said friction clutch mem-ber, to be biased'in a position blocking axial advance of said sleeve to positive clutching position until synchronization is substantially complete. i

17. In a synchronizing transmission,l coaxial driving members each carrying a set of clutch teeth and a friction clutch element, means drivingly connecting said members together for rotation at different speeds, a driven member adapted to selectively receive a drive from said driving members, a hub structure mounted on said driven member for rotation therewith, a shift device driven with said hub structure and having clutch teeth adapted to selectively clutch with said sets of clutch teeth. a synchronizing control structure disposed between eachoi' said driving members and said hub structure, each of said control structures hayinga friction clutch part engageable with one of said friction clutch elements and a stop for controllingv shift of said shift device, means drivingly connecting said control structures with said hub structure for accommodating axial and rotative movements of. said control structures relative to said hub structure; and means releasably connecting said shift device with said control structures for selective shift of said control structures by said shift device to eiTect selective engagement of said friction clutch parts respectively with said friction clutch ele-V ments, said releasable connecting means accommodating additional shift of Asaid shift device relative to said control devices for effecting selective clutching of the device with said sets of clutch teeth.

18. A synchronizing transmission according to V the preceding claim, wherein rthe releasable connecting means comprises an element releasably engaging said shift device and adapted for selective axial displacements in transmitting shifting movement from said shift device selectively to said control structures.

19. In a synchronizing transmission, coaxial` driving members each carrying a set of clutch teeth and a friction clutch element, means drivingly connecting said members for rotation at different speeds, a driven member 'adaptedfto selectively receive a drive from said driving members, a hub structure mounted-on said driven member for rotation therewith, `a shiftablesleeve splined uponl said hub structure and having clutch teeth adapted to selectively clutch with said sets of clutch teeth, a synchronizing control clutch teeth of the shift structure disposed between each of said driving members and said hub structure, each of said control structures having a friction clutch part engageable with one of said friction clutch ele- 5 ments and a stop for controlling shift of said `.shift device, ymeans drivingly connecting said control structures with said hub structure for accommodating axial and rotative movement of said control structures Frelative to said hub structure,l and an expansion ring releasably engaging the interior of said shiftable sleeve so as to receive shifting thrust therefrom and adapted to transmit such thrust to either of said control structures selectively so as to eifectA selective l5 engagement of said friction l tively with said friction clutch elements, said iexpansion ring accommodating additional shift of said shift device relative to said control devices teeth of the shift device with said sets of clutch teeth.

20. In a synchronizing mechanism, two relatively rotatable parts to be clutched one having a 'set of clutch teeth and a friction clutching member rotating therewithI and the other having a friction clutching element rotating therewith and adapted for displacement to engage the friction clutching member, the last said part having external splines, a hollow shift sleeve having at least a portion of its interior surface splined for radially expanding ring in releasable thrust receiving engagement with the interior of said shift sleeve for shift therewith to eil'ect said displacement of said friction clutching element and accommodate further shift of saidshift sleeve to clutch the latter with-said set of clutch teeth.

21. In a synchronizing transmission, a pair of coaxial'otatable parts to be drivingly connected,

40 Jaw and friction clutch members drivingly associated with' one of said parts, a hub element mounted upon the other part, a jaw clutch sleeve encircling, drivingly connected 'to and axially shiftable upon the periphery' of said hub element into positive. clutching engagement with said-jaw clutch members so as to establish a positive drive connection between said parts, a synchronizer element adapted under axial pressure to establish a synchronizing frictional driving connection with said friction clutch member, and including blocking means adapted as the result of frictional engagement between saidl synchronizer element and friction clutch member to bebiased in a position blocking axial advance of said sleeve, one of said elements being provided with a lug and the other of said elementsl having adapted to transmit to-,said synchronizer element the thrust received from said sleever during shifting Voi'l the latter. 05 f HENRY 1r Romanze.

clutch parts respecvfor effecting selective clutching ofthe clutchn sliding twith said external splines, and a a thrust member in releasable.'

engagement with the` interior of 

